I need to use some entity values in an extended property, but the offline app module keeps the value given by the CreateSampleRecord action, instead of using the cahed values.

Example: I have an offlineListRecords, inside there is a Container with an extended property using a value that populates the offlineListRecords. (I have the offline property also set in that container)

Unfortunately the Offline Apps component currently doesn't support replacing values *anywhere*. It only replaces the contents of expressions, inputs, link titles, image sources and image alt descriptions. These limitations were introduced to reduce the scope of DOM elements that we need to inspect, after we found some performance issues rendering large lists.
We'll keep your issue in mind when we revisit that particular code but, in short-term, it's unlikely that we'll support that.

I hope you wee able to work around this issue and I apologise for the late reply.